(a) Field of the Invention
The present invention relates to a liquid crystal display including a plurality of data drivers in a master-slave configuration and a driving method thereof.
(b) Description of the Related Art
In recent years, light and slim display devices are required as personal computers or television sets become light weight and slim. Since flat panel displays such as liquid crystal displays (LCDs), which satisfy such requirements, are developed and put to practical use in a variety of fields instead of cathode ray tubes (CRTs).
A typical LCD includes a plurality of pixels arranged in a matrix and each pixel includes a liquid crystal (LC) capacitor and a switching element connected thereto. The LC capacitor includes a liquid crystal layer having dielectric anisotropy and two field-generating electrodes for generating electric field in the LC layer. Since LC molecules in the LC layer have orientations depending on the strength of the applied electric field and the transmittance of light incident on the LC layer depends on the molecular orientations, the LCD can display desired images by adjusting the voltages applied to the field generating electrodes. The switching elements selectively transmit data voltages to the LC capacitors and the LCD further includes a plurality of gate lines transmitting gate signals for controlling the switching elements and a plurality of data lines for transmitting the data voltages to the switching elements. The gate signals and the data signals are provided by a gate driver and a data driver, which are controlled by a signal controller.
A dual driving technique, which arranges data drivers at upper and lower sides of the panels, is generally employed for a large, high-resolution LCD. Since each data driver is supplied with image data and control signals for displaying the image data, a pair of printed circuit boards (PCBs) for the provision of the image data and the control signals are required to be placed near the respective data drivers, and this yields the increase of the volume and the manufacturing cost of the LCD.
The data drivers for an LCD connected in a master-slave configuration are suggested for solving the above-described problems. A pair of data drivers in a master-slave configuration have different functions. For example, a slave data driver applies pre-charging voltages to data lines and a master data driver applies expected data voltages to the data lines. In detail, after the slave data driver drives the data lines with a predetermined voltage in a time of a horizontal period, the master data driver drives the data lines with the data voltages in the remaining time of the horizontal period. Accordingly, the slave data driver has a simple configuration for applying a fixed voltage. As a result, the master-slave configuration data drivers do not require a PCB for the slave data driver and further allows the slave data driver to be mounted on the liquid crystal panel in a SOG (silicon on glass) manner.
However, when the difference between a pre-charging voltage and a following data voltage for a pixel is too large to sufficiently charge the pixel to the data voltage for a given time, the image quality of the LCD is deteriorated.